Arsène Wenger had used his programme notes to claim that he now has a 25-man Arsenal squad of unprecedented and identical quality, but this was still a sobering reminder that some of his players are rather more equal than others.

Take Samir Nasri. He has been the outstanding player this season, not just for Arsenal but arguably in the entire Premier League, so the sight of him hobbling from the pitch after just 32 minutes while clutching his hamstring was particularly alarming.

Nasri’s departure coincided with a loss in momentum for Arsenal on Sunday but far more serious is the news that he is expected to be out for around three weeks so is almost certain to miss the first leg of the Champions League tie against Barcelona on Feb 16.

For Wenger, the frustration was compounded by the fact that he had originally intended to rest Nasri ahead of Tuesday’s Premier League match against Everton.

“It looks a serious hamstring injury,” said Wenger. “I have regrets now. The plan was to play Tomas Rosicky but he was still too weak because he was sick so I took a gamble on Nasri. It backfired. It is a big blow. We are at the stage where we play so many games, so to lose bodies is very difficult for us.”

Another lost body for at least one match is Sébastien Squillaci who, having returned to play for the first time in more than a month, was again unconvincing and lasted only 42 minutes before being deservedly dismissed for blocking Jack Hunt as he ran clear on goal.

It leaves Arsenal with only two senior centre-backs for the game against Everton but, having again concluded that most Premier League defenders are over-priced, Wenger is unlikely to do any business before the transfer window closes.

Despite it being their ninth match in January, Arsenal started fairly brightly, with Andrei Arshavin and Nicklas Bendtner both creating a flurry of first-half chances.

Bendtner was particularly profligate, shooting wide from the edge of the six-yard box and then missing the ball completely when Nasri had split the Huddersfield defence with a brilliantly-lofted pass. That miss attracted derision from the Huddersfield supporters but they were silenced in the next attack when Bendtner’s shot fortuitously deflected off Peter Clarke and flew past goalkeeper Ian Bennett. Replays also suggested that Marouane Chamakh had handled the ball in the build-up to the goal.

Bendtner, though, still could not resist running past the visiting supporters with one hand cupped against his ear.

Huddersfield responded admirably and, with Nasri off and Arsenal down to 10 men following Squillaci’s red card, they placed their opponents under sustained pressure.

Anthony Pilkington, Jamie McCombe and Joey Gudjonsson all missed good chances while Alan Lee forced one outstanding diving save from Manuel Almunia, playing his first match since September.

With Huddersfield dominating, the equaliser was thoroughly merited, and it was predictable that it should come from a set-piece.

Pilkington’s corner was well directed to the edge of the six-yard box and, with Abou Diaby failing to get much height on his jump, Lee headed powerfully past Almunia.

Wenger responded by introducing Cesc Fabregas and Arsenal duly resumed control. The winner, though, was also controversial, with McCombe getting the wrong side of Bendtner after Fabregas’s cute pass. The subsequent contact was minimal but it was enough to disrupt Bendtner and persuade referee Mark Clattenburg to award a penalty.

Fabregas then did little for his own popularity by furiously encouraging Clattenburg to brandish his second red card of the match, before scoring with ease from the spot.

The bad blood engendered by that moment spilled over after the game, when Pilkington used his Twitter account to allege that Fabregas had sworn at and refused to exchange shirts with some of his team-mates. However, Pilkington quickly withdrew the message and his account was closed down.

Victory preserved Wenger’s record of never having lost an FA Cup tie against a lower-league club. “It shows how seriously we take the competition,” he said.